Wireless communication systems are developing to provide users with various services such as broadcasting a multimedia video, a multimedia message, and such. Particularly, next-generation wireless communication systems are developing to provide a data service of 100 Megabits per second (Mbps) or more to users who move at high speed, and provide a data service of one (‘1’) Gigabit per second (Gbps) or more to users who move at low speed.
To satisfy a wireless service demand amount for providing various services, a method for increasing not only a user data service capacity but also a network service capacity is needed. Accordingly, to increase the network service capacity, the wireless communication system can construct a heterogeneous network using a low output small BS. For instance, a heterogeneous network using a low output pico cell, femto cell, and relay station (RS) is constructed as illustrated in FIG. 1 below.
FIG. 1 illustrates a construction of a heterogeneous network according to the conventional art.
As illustrated in FIG. 1, pico BSs 110 and 120, a femto BS 130, and an RS 140 are installed within a macro cell managed by a macro BS 100.
Pico cells managed by the pico BSs 110 and 120 can be installed within a hot zone where there are many data service requests. A femto cell managed by the femto BS 130 can be installed in an indoor office or a home. The RS 140 can be installed for use of supplementing a service area of the macro cell.
The heterogeneous network constructed as above can enhance a network capacity at low cost because a plurality of small BSs form a small scale cell and reuse resources.
A mobile station (MS) of a wireless communication system selects a serving cell based on a reception quality of a cell identification signal. Due to interference caused by a signal of a high output macro BS, there is a problem in that the MS has difficulty selecting a low output small BS. That is, the MS can select a small BS only in a restricted area where a signal strength of the small BS is superior to a signal strength of a macro BS. Accordingly, a service area of the small BS decreases to the restricted area where the signal strength of the small BS is superior to the signal strength of the macro BS, so a gain following the introduction of the small BS is reduced.